LED Driving Circuit Current Compensation for Brightness Stability
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Solution Overview
Problem
Maintaining the brightness of mass-produced active matrix (AM) mini-LEDs over long-term use is challenging due to their current-driven nature and the complexity of controlling display brightness with multiple transistors in each pixel.
Innovation Solution
A method involving an LED driving circuit capable of current detection and compensation, which maps relationships between current, brightness, and voltage, allowing real-time monitoring and voltage adjustments to maintain LED brightness, and storing these relationships in memory for data-driven compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If AM driving type with multiple transistors per pixel is used, then display resolution and control capability are improved, but brightness maintenance and manufacturing precision deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the driving circuit continuously monitors the actual current through each mini-LED and compares it with the target current value. Based on this comparison, the circuit automatically adjusts the driving voltage to compensate for brightness degradation, ensuring consistent display performance over time despite the complex multi-transistor architecture
Solution Approach 2:
The driving circuit performs self-calibration by automatically detecting actual current values and adjusting driving parameters without requiring external intervention. The system stores mapping relationships between voltage, current, and brightness in memory, enabling the circuit to autonomously maintain optimal display characteristics throughout its operational life
2Reliability
If current detection and compensation circuit is added, then brightness maintenance is improved, but device complexity increases
Solution Approach 1:
The patent merges the current detection function with the existing driving circuit by utilizing the same transistor structure for both driving and sensing purposes. The detection transistor shares the same gate control as the driving transistor, allowing current monitoring to be integrated into the existing pixel structure without adding separate dedicated sensing circuits
Solution Approach 2:
The driving transistor serves dual functions: it controls the LED current during normal operation and acts as a sensing element for current detection during compensation mode. This multi-functionality reduces the need for additional dedicated sensing components, thereby limiting the increase in device complexity while maintaining brightness stability
Data Source
AI summary
A method for maintaining LED brightness is provided and exemplarily includes steps of: providing a LED driving circuit capable of performing current detection and compensation; performing a detection based on the LED driving circuit to obtain mapping relationships among current, brightness and voltage; and monitoring a current flowing through a LED driven by the LED driving circuit, and performing a compensation according to the monitored current and the mapping relationships to maintain brightness of the LED. Moreover, a LED driving circuit is also provided and includes first through fourth transistors and a capacitor. In addition, a display device adopting the method for maintaining LED brightness or the LED driving circuit is also provided.